A well-prepared California hiker missing for six days in the icy backcountry of Yosemite National Park was found in good health after an extensive search, officials said.

A helicopter crew spotted Alan Chow on Friday above Wapama Falls near the centre of the park, where overnight temperatures dipped below freezing, the National Park Service said.

Park Ranger Scott Gediman told San Francisco Bay Area news station KTVU-TV that the 36-year-old Oakland resident got lost because usually well-marked trails were covered in snow.

Chow had done everything right to survive – he was prepared and didn’t “try to walk around and get even more lost,” Gediman said.

He “did the right thing by setting up his tent, using melted snow for drinking water, had some food, had warm clothing and was able to stay put,” the ranger said.

Chow, an avid outdoorsman, planned an overnight backpacking trip alone and was last seen February 17. He wasn’t officially noticed as missing until three days later when Chow didn’t show up for his job at the Alameda County Social Services Agency and a co-worker became concerned.

The search effort included as many as 60 people, who focused on the area near the Hetch Hetchy Reservoir, where Chow was last seen.

Chow is said to be in good condition and was reunited with his family, according to the park service.